This invention relates generally to pressurized dispensing containers and more particularly relates to an improved, product-isolating, collapsable liner for such containers.
Aerosol containers are extensively used for storing, marketing and conveniently dispensing a great variety of products.
For some products it has been found desirable to provide a liner within the relatively rigid outer container in order to separate the product from the propellant. Ordinarily the product is contained within the liner and the propellant surrounds the liner so that the liner collapses under the influence of the propellant as product is expelled through a valve formed in communication with the interior of the liner. Usually, the valve is manually operable and is mounted in a closure which is secured to the top of the outer container.
Pressurized dispensing containers having a liner are commonly known as barrier packs. There are two areas of barrier pack design considerations which are important in evaluating the commercial desirability of a barrier pack container. The first is the ease, convenience and economical efficiency of the assembly of the barrier pack components and the filling of the barrier pack container with product and propellant. The second is the efficiency with which the barrier pack container is able to expell the contained product, that is, the proportion of contained product which can be expelled.
Conventional aerosol containers, of the type which do not have an interior lining, arrive at the filling machine in two parts. The first part is the main body of the container as supplied by the container manufacturer. It has a cylindrical side wall portion, an attached bottom and an attached crown. The crown has a relatively large open mouth or filler hole at its central top which is bounded by a filler ring formed by an annular, outward curl. The second part of the conventional aerosol container is a valve closure carrying a manual valve dispensing mechanism. The filling machine inserts the product and propellant into the main body of the container through the filler hole and then crimps the valve closure to the filler hole of the crown to seal the two parts together.
Because of the design of some product-isolating liners, very substantial modifications in this process have been necessary therefore reducing the economic desirability of using such liners. For example, some liners must be inserted prior to the attachment of the crown or the bottom to the cylindrical side walls of the outer container. Some liners require a small propellant filler hole in the bottom of the container which must be sealed by a plug after the propellant is filled into the container.
There is, therefore, a need for an improved barrier pack liner requiring minimal modification of the conventional filling operation, which may be inserted through the conventional filler hole of the main container body and which will allow both product and propellant to be filled into the container through the filler hole.
Any container liner, when entirely collapsed, will nonetheless retain some product between its interior walls. If, during collapse of the liner, the interior walls come together to pinch off and isolate a region of product, then a substantial volume of product will be unable to be exhausted from the container. In order to avoid such pinch off, containers have been annularly or longitudinally pleated in order to provide for their orderly collapse and to minimize the residual volume of unexpellable product. However, because of the substantial thickness of the accumulated folded pleats as they fold together, a significant, central, interior volume of unexpellable product remains in such pleated liners. This is especially true of annularly pleated liners. There is therefore, a need for a liner which can further reduce the volume of residual unexpellable product.
One limitation of previously known pleated liners is that they place severe limitations on the shape of their outer containers. For example, the annularly pleated liner is limited to cylindrical containers or to conically shaped containers having the valved closure at its large end. The longitudinally pleated liner permits a greater variety of outer container shapes but requires that a particular liner be manufactured for a particularly shaped container.
There is, therefore, a need for a single liner which can conform to a variety of container shapes.